#include <windows.h>
#include <winbase.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/timeb.h>

#ifdef __GNUC__
static long _dstbias=0;
#endif

void win32_tzset( void )
{
	tzset();

	if (((char*)getenv("TZ") == (char*)NULL) && (_timezone == 0))
	{
		TIME_ZONE_INFORMATION tzinfo;
		DWORD tzstate;
		int dstflag=0;
		static char TZ[40];
		char tmp_str[40];
		long i,j,g,k;
		
		/* printf("try to build up a TZ Variable from Windows Date Control Panel!\n"); */
		if ( (tzstate = GetTimeZoneInformation( &tzinfo )) != 0xFFFFFFFF )
		{
		/*
		* Must be very careful in determining whether or not DST is
		* really in effect.
			*/
			if ( (tzstate == TIME_ZONE_ID_DAYLIGHT) &&
				(tzinfo.DaylightDate.wMonth != 0) &&
				(tzinfo.DaylightBias != 0) )
				dstflag = 1;
			else
			/*
			* When in doubt, assume standard time
			*/
			dstflag = 0;
		}
		else
			dstflag = 0; /* When in doubt, assume standard time */
		
		_timezone = tzinfo.Bias * 60L;
		
		if ( tzinfo.StandardDate.wMonth != 0 )
			_timezone += (tzinfo.StandardBias * 60L);
		
		if ( (tzinfo.DaylightDate.wMonth != 0) &&
			(tzinfo.DaylightBias != 0) )
		{
			_daylight = 1;
			_dstbias = (tzinfo.DaylightBias - tzinfo.StandardBias) *
				60L;
		}
		else 
		{
			_daylight = 0;
			_dstbias = 0;
		}
		
		_tzname[0] = "GMT";
		_tzname[1] = "DST";
		
		/* BUILD UP TZ STRING */
		/* always relativ to GMT Time */
		
		strcpy(TZ,"TZ=GMT"); /* probably UTC for Universal StandardTime */
		
		if (_timezone > 0)
		{
			strcat(TZ,"+");
			i=_timezone;
		}
		else
		{
			strcat(TZ,"-");
			i=_timezone * -1;
		}
		j=i % 60L; /* Minutenausgleich */
		g=j % 60L; /* Sekundenausgleich */
		i=i / 3600L; 
		
		sprintf(tmp_str,"%ld", i);
		strcat(TZ,tmp_str);
		
		if (j | g)
		{
			sprintf(tmp_str,":%ld", j);
			strcat(TZ,tmp_str);
		}
		
		if (g)
		{
			sprintf(tmp_str,":%ld", g);
			strcat(TZ,tmp_str);
		}
		
		
		if (_daylight)
		{
			strcat(TZ,"DST"); /* DaylightSavingTime */
			
			k=_timezone + _dstbias; /* absolut differenz */
			
			if (k > 0)
			{
				strcat(TZ,"+");
				i=k;
			}
			else
			{	
				strcat(TZ,"-");
				i=k * -1;
			}
			j=i % 60L; /* Minutenausgleich */
			g=j % 60L; /* Sekundenausgleich */
			i=i / 3600L; 
			
			sprintf(tmp_str,"%ld", i);
			strcat(TZ,tmp_str);
			
			if (j | g)
			{
				sprintf(tmp_str,":%ld", j);
				strcat(TZ,tmp_str);
			}
			if (g)
			{
				sprintf(tmp_str,":%ld", g);
				strcat(TZ,tmp_str);
			}
			
			
			/* when to switch DST on ?*/
			sprintf(tmp_str,",M%d.%d.%d/%d",
				tzinfo.DaylightDate.wMonth,
				tzinfo.DaylightDate.wDay,
				tzinfo.DaylightDate.wDayOfWeek
				tzinfo.DaylightDate.wHour);
			strcat(TZ,tmp_str);

			if (tzinfo.DaylightDate.wMinute || tzinfo.DaylightDate.wSecond)
			{
				sprintf(tmp_str,",:%d", tzinfo.DaylightDate.wMinute);
				strcat(TZ,tmp_str);
			}
			if (tzinfo.DaylightDate.wSecond)
			{
				sprintf(tmp_str,",:%d", tzinfo.DaylightDate.wSecond);
				strcat(TZ,tmp_str);
			}
		    
			
			/* when to switch DST off, back to StandardDate ?*/
			sprintf(tmp_str,",M%d.%d.%d/%d",
				tzinfo.StandardDate.wMonth,
				tzinfo.StandardDate.wDay,
				tzinfo.StandardDate.wDayOfWeek,
				tzinfo.StandardDate.wHour);
			strcat(TZ,tmp_str);

			if (tzinfo.StandardDate.wMinute || tzinfo.StandardDate.wSecond)
			{
				sprintf(tmp_str,",:%d", tzinfo.StandardDate.wMinute);
				strcat(TZ,tmp_str);
			}
			if (tzinfo.StandardDate.wSecond)
			{
				sprintf(tmp_str,",:%d", tzinfo.StandardDate.wSecond);
				strcat(TZ,tmp_str);
			}
		}
		
		/* printf("\nbuild up TZ string: TZ=%s\n", TZ); */
		putenv(TZ);
		setenv
	}
	tzset(); /* set to system & cygwin */
}